Morphine: single-dose tolerance.
Rats show a significant degree of tolerance to a second dose of morphine, with the degree of tolerance increasing the longer the delay between the two doses of morphine. To measure the morphine effect a foot-shock attenuation procedure that allowed the animal to adjust the shock intensity was used in studying delays of up to 180 days.
D000818:Animals; D004361:Drug Tolerance; D004597:Electroshock; D004924:Escape Reaction; D005528:Foot; D007279:Injections, Subcutaneous; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors
D009020:Morphine